An area detector diffractometer facility for protein crystallography is being designed, built and tested. When finished, the facility will record x-ray diffraction data at least 20 times faster than a conventional diffractometer. The x-ray detectors are multiwire proportional chambers each with sensitive area 25cm x 25cm, and with position resolution 1mm x 2mm. Each will be capable of recording data at a rate of 150 kHz. There ultimately will be as many as four detectors, but a complete system operating with one detector will first be built. The facility will allow the study of crystals with unit cell sizes up to 300A. It will be available for use by all x-ray crystallographers interested in macromolecules.